Failure notification is an important part of Operation, Administration and Maintenance (OAM) in conventional data networks to enable quick failure detection and an ability to take action to correct the failure. When a fault condition occurs, an intermediate node logically adjacent to the fault generates and sends an Alarm Indication Signal (AIS) downstream to a downstream endpoint. Conventionally, only transit nodes (i.e., nodes other than endpoint nodes) generate AIS messages to identify faults in the server sub-layer. The AIS informs the downstream endpoint of the failure and triggers a reaction to the fault. Conventional implementations of AIS are detailed in Internet Engineering Task Force Request for Comments #6371 and #6427, which is incorporated by reference herein in its entirety. However, conventional techniques fail to address propagating the fault information upstream to the other end of the network to coordinate failure protection by both ends.
The conventional preferred method of live connectivity monitoring uses a Bidirectional Forwarding Detection (BFD) mechanism to inform the upstream endpoint of the failure. When an AIS message is received by the downstream endpoint, the downstream endpoint determines which upstream tunnel is associated with the failed downstream tunnel. The downstream endpoint then checks to see if BFD is configured on the upstream tunnel. If BFD is configured on the upstream tunnel, the downstream endpoint informs BFD that the downstream endpoint needs to send a Remote Defect Indication (RDI) to the upstream endpoint. Upon receiving a BFD message with RDI, the upstream endpoint will perform failure protection.
There is no operational requirement that an operator has to run BFD in their network. In addition, less sophisticated and inexpensive systems do not have sufficient capability to run BFD. Currently, BFD is the only method available to send failure notification upstream in an associated data network tunnel. BFD is a resource-intensive protocol that uses resources that are generally not available on less sophisticated and inexpensive networks, and is not scalable on sophisticated and expensive networks. Further, running BFD for the sole purpose of failure notification is a significant waste of resources. However, if the data network is not configured to implement BFD or other fault synchronization technology, then, currently, there is no way to synchronize the fault.
Conventional techniques and devices suffer from problems including high cost, lack of scalability, severely limited alternative solutions, high resource usage, and high energy consumption.
Accordingly, there are long-felt industry needs for methods and apparatus that improve upon conventional methods and apparatus, including methods and apparatus that optimize fault synchronization in a bidirectional data network.